Holographic display panel, holographic display device and display method therefor

ABSTRACT

A holographic display panel comprises a plurality of display units, each display unit comprises at least two adjacent pixels, each pixel comprises: a plurality of sub-pixels; and a plurality of phase plates. Diffractive angles of light coming out of the phase plates corresponding to the sub-pixels in a same pixel are the same, a diffractive angle of first light coming out of the phase plates corresponding to a first pixel in one of the display units is different from a diffractive angle of second light coming out of the phase plates corresponding to a second pixel that is different from the first pixel but in the same display unit, and a reverse extension line of the first light and a reverse extension line of the second light intersect at an image plane position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Section 371 National Stage Application ofInternational Application No. PCT/CN2017/093392, filed on 18 Jul. 2017,entitled “HOLOGRAPHIC DISPLAY PANEL, HOLOGRAPHIC DISPLAY DEVICE ANDDISPLAYING METHOD THEREFOR”, which claims priority to ChineseApplication No. 201610815306.1, filed on 9 Sep. 2016, incorporatedherein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of display technologies, andparticularly, to a holographic display panel, a holographic displaydevice having the holographic display panel and a holographic displaymethod for the holographic display device.

BACKGROUND

With continuous development of display technologies, three-dimensional(3D) display technologies have been more and more widely used. Duringthe process of realizing a 3D display, the left eye and the right eye ofa user can receive different images, and the two images may constitute apair of stereoscopic images having a horizontal parallax, and with imagefusion effect of the brain, a stereoscopic image having a certain depthof field is finally formed. However, since the images received by theleft eye and the right eye of the user are different from each other,the user may easily feel dizzy after watching a 3D display image for along time.

SUMMARY

An object of the present disclosure is to provide a holographic displaypanel, a holographic display device and a display method therefor, toovercome or alleviate at least one aspect of the disadvantages mentionedabove.

According to one aspect of the present disclosure, there is provided aholographic display panel.

According to an exemplary embodiment, the holographic display panelcomprises a plurality of display units, and each of the plurality ofdisplay units comprises at least two adjacent pixels each comprising aplurality of sub-pixels. Each of the plurality of display units furthercomprises a plurality of phase plates, each sub-pixel of the pluralityof sub-pixels corresponding to one of the plurality of phase plates in alight exit direction of the each sub-pixel, the plurality of phaseplates being configured to control diffractive angles of light comingout of the plurality of phase plates. Diffractive angles of light comingout of the phase plates corresponding to the sub-pixels in one samepixel are the same, a diffractive angle of first light coming out of thephase plates corresponding to a first pixel in one of the plurality ofdisplay units is different from a diffractive angle of second lightcoming out of the phase plates corresponding to a second pixel that isdifferent from the first pixel and is in the same display unit as thefirst pixel, and a reverse extension line of the first light and areverse extension line of the second light intersect at an image planeposition.

According to another exemplary embodiment, the plurality of displayunits may be divided into a plurality of display groups arranged into anarray, each of the plurality of display groups is consisted of at leasttwo display units, and the at least two display units are locatedadjacent to each other. Image plane positions of the display units in asame one of the plurality of display group are different from eachother.

According to another exemplary embodiment, one display unit of theplurality of display units may have an image plane position differentfrom an image plane position of any one of display units adjacent to theone display unit.

According to another exemplary embodiment, each pixel may comprise afirst sub-pixel, a second sub-pixel and a third sub-pixel. Firstsub-pixels, second sub-pixels and third sub-pixels in the holographicdisplay panel are arranged in two adjacent rows. The first sub-pixelsand the second sub-pixels are arranged alternately in one row of the twoadjacent rows, and the other row of the two adjacent rows is constitutedonly by the third sub-pixels. The third sub-pixel of each pixel islocated between the first sub-pixel and the second sub-pixel of the samepixel in a direction of the row.

According to another exemplary embodiment, the sub-pixels of each pixelmay be arranged in a same row.

According to another exemplary embodiment, the plurality of phase platesmay be transmission gratings.

According to another exemplary embodiment, the holographic display panelmay further comprise an array substrate and a color filter substratedisposed opposite to the array substrate. The color filter substratecomprises a color filter layer and the plurality of phase plates, andthe plurality of phase plates are disposed at a side of the color filterlayer close to or facing away from the array substrate.

According to another aspect of the present disclosure, there is provideda holographic display device.

According to an exemplary embodiment, the holographic display device maycomprise the holographic display panel according to any one of the aboveembodiments.

According to another exemplary embodiment, the holographic display panelmay comprise a liquid crystal display panel and a collimated backlightsource configured to provide backlight to the liquid crystal displaypanel.

According to a further aspect of the present disclosure, there isprovided a holographic display method.

According to an exemplary embodiment, the holographic display method maybe used for the holographic display device according to any one of theabove embodiments. The holographic display method may comprise obtainingcoded information of a holographic image. The coded informationcomprises a gray scale value of each pixel in each feature area of theimage, and the gray scale value is superimposed with image planeposition data of the feature area. The image plane position data of onefeature area indicates only one image plane position. The holographicdisplay method further comprises: converting the gray scale value ofeach pixel into voltage data of each sub-pixel in the pixel; andcharging each sub-pixel in the pixel in accordance with the voltage dataduring progressively scanning rows of sub-pixels.

According to another exemplary embodiment, the plurality of displayunits are divided into a plurality of display groups arranged into anarray, each of the plurality of display groups is consisted of at leasttwo display units having different image plane positions, each of theplurality of display units comprising at least two adjacent pixels, animage plane position indicated by image plane position data of thefeature area is different from an image plane position of any of theplurality of display units. The method of superimposing an image planeposition of the feature area to obtain the gray scale value of eachpixel in the feature area comprises: selecting and turning on one pixelof each display unit of the at least two different display units,wherein reverse extension lines of light coming out of the phase platescorresponding to the pixels that are turned on intersect at an imageplane position indicated by the image plane position data of the featurearea.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1a is an illustrative drawing showing a process of recording aholographic image;

FIG. 1b is an illustrative drawing showing a process of reproducing theholographic image shown in FIG. 1a and recorded on a holographic plate;

FIG. 2 is an illustrative drawing showing a working principle of aholographic display panel according to an embodiment of the presentdisclosure, and schematically showing reproducing of the holographicimage and setting an image plane position of the reproduced image;

FIG. 3 is an illustrative drawing showing a display unit according to anembodiment of the present disclosure and showing that reverse extensionlines of light exiting from phase plates of different pixels intersectat an image plane position;

FIG. 4a shows an embodiment of the phase plate of the presentdisclosure, wherein the phase plate is a single-order grating, and FIG.4a further illustratively shows a diffraction process of light passingthrough the phase plate;

FIG. 4b shows another embodiment of the phase plate of the presentdisclosure, wherein the phase plate is a multi-order grating;

FIG. 5 is an illustrative drawing showing a holographic display deviceaccording to an embodiment of the present disclosure;

FIG. 6 is an illustrative drawing showing a holographic display deviceaccording to another embodiment of the present disclosure;

FIG. 7 is an illustrative drawing, showing a principle of realizingsetting of the image plane position by combining pixels of two differentdisplay units;

FIG. 8 is an illustrative drawing showing a holographic display deviceaccording to still another embodiment of the present disclosure;

FIG. 9 is an illustrative drawing, showing a principle of realizingsetting of the image plane position by combining pixels of threedifferent display units;

FIG. 10 is an illustrative drawing showing an arrangement of sub-pixelsaccording to an embodiment of the present disclosure;

FIG. 11 is an illustrative drawing showing an arrangement of sub-pixelsaccording to another embodiment of the present disclosure;

FIG. 12 is an illustrative drawing showing a principle of achieving aholographic display of a holographic display device according to anotherembodiment of the present disclosure; and

FIG. 13 is a flowchart of a display method of a holographic displaydevice according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of the present disclosure will be describedhereinafter in detail with reference to the attached drawings, whereinthe like reference numerals refer to the like elements. The presentdisclosure may, however, be embodied in many different forms and shouldnot be construed as being limited by the embodiment set forth herein;rather, these embodiments are provided so that the present disclosurewill be thorough and complete, and will fully convey the concept of thedisclosure to those skilled in the art.

In order to solve the problems mentioned in the background part of thepresent disclosure, there exists a holographic display technology, whichcan make images received by left eye and right eye of a user consistentwith each other. A specific process of such holographic display isbriefly introduced as follows.

As shown in FIG. 1, light emitted by a laser 21 is divided into twobeams, one of the beams irradiates to an object 22 and is reflected andscattered on a surface of the object 22, reflected light and scatteredlight from the surface of the object 22 arrive at a holographic plate 23and then form an object light wave A. The other light beam, used as areference light wave B, irradiates to the holographic plate 23 andexposes the holographic plate 23, so that the holographic plate obtainsan interference image having all information of the object light wave A,such as amplitude and phase, is recorded. Then, as shown in FIG. 1b , areproducing light wave C (which is the same as the above-mentionedreference light wave B) is used to irradiate the holographic plate 23 onwhich all information of the object light wave is recorded, such thatthe original object light wave A can be reproduced, thereby a vividstereoscopic virtual image 24 is displayed. When the reproducing lightwave C is the same as a conjugate light wave of the reference light waveB, a real image 25 of the object 22 can be obtained, and usually in theholographic display technology, what a user sees is the above-mentionedvirtual image 24.

The holographic plate 23 is provided thereon with a photosensitivematerial, therefore during the process of exposing the holographic plateby the reference light wave B, all information of the object light waveA can be recorded. However, since the amplitude and phase recorded onthe exposed holographic plate 23 cannot be changed, only onestereoscopic image can be displayed. Based on that, even if asuperposition exposure is performed on the holographic plate 23, thenumber of formed interference images is limited, thus a dynamicholographic display cannot be achieved, and user experience on theholographic display is getting worse.

FIG. 2 shows a holographic display panel according to an embodiment ofthe present disclosure. The holographic display panel comprises aplurality of display units 10, each display unit 10 comprises at leasttwo adjacent pixels 101, and each pixel 101 comprises a plurality ofsub-pixels 1011, as shown in FIG. 3.

Type and number of sub-pixels 1011 in one pixel 101 may vary as desired.For example, one pixel 101 may include three sub-pixels 1011, which maybe a red sub-pixel, a green sub-pixel and a blue sub-pixel respectively,or which may be a magenta sub-pixel, a cyan sub-pixel and a yellowsub-pixel. In another example, in addition to the red sub-pixel, thegreen sub-pixel and the blue sub-pixel, the pixel 101 may also include awhite sub-pixel or a yellow sub-pixel.

Before display, encoded information of a holographic image obtainedthrough hologram calculation may be converted into voltage data appliedto each sub-pixel of a pixel. When the holographic image changes, theencoded information changes as well, and the voltage data applied toeach sub-pixel changes as well, such that a dynamic holographic displaycan be achieved.

As shown in FIG. 3, each display unit 10 further includes a plurality ofphase plates 102, and each sub-pixel 1011 is aligned with one of thephase plates 102 along its light outcoming direction. The phase plates102 are used to control diffractive angles β of light exiting from thephase plates 102. A diffractive angle β is an included angle between adirection of light coming out of the phase plate 102 and a direction ofincident light to the phase plate 102.

Light passing through phase plates 102 corresponding to sub-pixels 1011of a same pixel 101 has a same diffractive angle β, and light passingthrough phase plates 102 corresponding to one pixel 101 of a displayunit 10 has a different diffractive angle β from that of light passingthrough phase plates 102 corresponding to another pixel 101 of the samedisplay unit 10.

According to the embodiment shown in FIG. 3, light emitted fromsub-pixels 1011 of one pixel 101 (for example, the left pixel 101) hasthe same diffractive angle after passing through phase plates 102corresponding to the sub-pixels 1011 respectively. Meanwhile, lightemitted from sub-pixels 1011 of the right pixel 101′ also has the samediffractive angle after passing through phase plates 102 correspondingto the sub-pixels 1011 respectively. However, in a same display unit 10,light emitted from the left pixel 101 is deflected leftward afterpassing through the phase plates 102, while light emitted from the rightpixel 101 is deflected rightward after passing through the phase plates102. Therefore, reverse extension lines of light emitted from the samedisplay unit 10 intersect at an image plane position DF1.

To be noted, since the phase plates 102 are used to diffract incidentlight, phase gratings (i.e., diffraction grating) can be used as thephase plates 102, and preferably, in order to improve utilization oflight, transmission gratings may be used as the phase plates 102.Because a phase of light at a convex portion of the transmission gratingis different from a phase of the light at a concave portion of thetransmission grating, the light can be diffracted when passing throughthe transmission grating.

The transmission grating may be a single order grating shown in FIG. 4aor a multi-order grating shown in FIG. 4b . A diffractive angle β ofm-order diffracted wave of the transmission grating is only determinedby a period P of the grating, the wavelength λ of an incident wave andan incident angle β0, i.e., sin β−sin β0=mπ/P (m=0, ±1, ±2, . . . ),thus, in a case that incident wave has a constant wavelength λ, thediffractive angle β may be adjusted through adjusting the period P ofthe transmission grating.

FIG. 5 shows an embodiment of the holographic display panel. As shown inFIG. 5, the holographic display panel comprises an array substrate 11and an opposite substrate 12 that are arranged opposite to each other,the opposite substrate 12 may include a color filter layer 103 and theabove-described phase plates 102. The phase plates 102 are arranged at aside of the color filter layer 103 close to the array substrate 11, andlight emitted from a backlight source 13 is diffracted by the phaseplates 102 first and then passes through the color filter layer 103. Inthis case, wavelengths λ of incident light to the phase plates 102 arethe same. In order that a diffractive angle of light emitted from onepixel 101 of a display unit 10 after passing through the phase plate 102corresponding to the one pixel is different from a diffractive angle oflight emitted from another or other pixels 101 in the same display unitafter passing through the phase plate 102 corresponding to the anotheror other pixels, periods (P) of the phase plates 102 corresponding todifferent pixels 101 in the same display unit 10 may be adjusted, suchthat the period of the phase plates 102 corresponding to one pixel 101is different from that of the phase plates 102 corresponding to anotheror other pixels 101.

FIG. 6 shows another embodiment of the holographic display panel. Asshown in FIG. 6, the structure shown in FIG. 6 differs from thestructure shown in FIG. 5 in that the phase plates 102 are arranged at aside of the color filter layer 103 facing away from the array substrate11. Light emitted from the backlight source 13 first passes through thecolor filter layer 103 and then arrives at the phase plates. With alight filtering effect of the color filter layer 103, light of differentcolors irradiates different phase plates 102. For example, in acondition of the pixel 101 including a red sub-pixel, a green sub-pixeland a blue sub-pixel, the pixel 101 can emit red light, green light andblue light. Since wavelengths λ of the red light, the green light andthe blue light are different from each other, wavelengths λ of incidentlight arrives at the phase plates 102 are different from each other. Inorder to make the light emitted by three sub-pixels 1011 in a same pixel101 (such as the left pixel 101) to have a same diffractive angle βafter passing through their respective phase plates 102, periods P ofthe three phase plates 102 corresponding to the three sub-pixels 1011need to be changed, such that the periods of the three phase plates 102are different from each other. For example, when a diffractive angle βof green light after passing through the phase plates 102 is used as areference, periods of phase plates 102 corresponding to red sub-pixelsneed to be increased and periods of the phase plates 102 correspondingto the blue sub-pixels simultaneously, because wavelength λ of red lightis longer than those of green light and blue light.

In summary, because there is a relationship λr>λg>λb among wavelength λrof red light, wavelength λg of green light and wavelength λb of bluelight, there is a relationship Pr>Pg>Pb existing among the period Pr ofthe phase plate 102 corresponding to the red sub-pixel, the period Pg ofthe phase plate 102 corresponding to the green sub-pixel and the periodPb of the phase plate 102 corresponding to the blue sub-pixel.Therefore, periods P of the phase plates 102 in the same display unit 10of FIG. 6 are different from each other.

Additionally, when the phase plates 102 are transmission gratings, itcan generate diffracted waves of m orders. For example, as shown in FIG.4a , the phase plate is a single-order grating, and it generatesdiffracted waves of 2 orders (m=2). Because 0-order diffracted wave isin a direction of the incident light, its diffractive angle β cannot beadjusted, thus the grating may be arranged such that a phase differencebetween the phase at bars of the grating and the phase at slits of thegrating is odd times of a half-wavelength, so that a destructiveinterference is generated in the 0-order diffracted wave, and an aim ofweakening the 0-order diffracted wave can be achieved. Additionally,diffracted waves having orders equal to or larger than ±2 are notobjects to be adjusted in the embodiment of the present disclosure,because their diffractive angle β are too large such that their lightintensities are relatively low. In summary, the diffracted waves to beadjusted in the embodiment of the present disclosure are ±1-orderdiffracted waves.

In another embodiment, the phase plate 102 is a multi-order gratingshown in FIG. 4b . The larger the number of steps of a single phasestage 1021 is, the higher the light extraction efficiency of ±1-orderdiffracted wave is, and the larger the energy of centrally emitted lightis. When the number of steps of the phase stage 1021 is less than 4, theeffect of increasing light extraction efficiency of ±1-order diffractedwave is not significant, and when the number of steps of the phase stage1021 is more than 8, although it can increase light extractionefficiency of ±1-order diffracted wave, manufacturing accuracy needs tobe improved, which goes against controlling production cost. Therefore,the number of steps of a single phase stage is preferably in a range of4 to 8, and FIG. 4b shows an embodiment wherein each phase stage has 4steps, which can facilitate controlling production cost and increasinglight extraction efficiency of ±1-order diffracted wave, so as toimprove display performance of holographic display.

In summary, by adjusting the period of the phase plate 102, adiffractive angle β of light passing through the phase plate 102 can beadjusted, such that the position (i.e., image plane position, forexample, image plane position DF1) of an intersection point of reverseextension lines of light emitted from the same display unit 10 can beadjusted, and thereby a distance between the image plane position and auser's eyes can be changed. A spatial position of a holographicallydisplayed image may be defined by the image plane position, such that animage reproduced by the holographic display panel may have a certainstereoscopic effect.

When the holographic display panel has a plurality of display units 10having image plane positions different from each other, the performanceof stereoscopic display would be better. A detailed description of aholographic display panel having such a structure is providedhereinafter.

Specifically, as shown in FIG. 2, the plurality of display units 10 inthe holographic display panel are divided into a plurality of displaygroups 01 arranged into an array, each display group 01 is consisted ofat least two display units 10, and the at least two display units 10 arearranged adjacent to each other. Image plane positions of display units10 in a same display group 01 are different from each other. Forexample, when one display group 01 is consisted of two display units 10having different image plane positions, an image plane position of oneof the two display units 10 is DF1, and an image plane position of theother display unit 10′ arranged in the same display group 01 as the onedisplay unit 10 is DF2.

As shown in FIG. 2, an image reproduced at the image plane position DF1is relatively closer to a user's eyes. Assuming that, in this condition,a distance between the image plane position DF1 and the user's eyes is18 cm to 22 cm, so that it is ensured that the user's eye can clearlysee the image which is relatively closer to the user's eyes. An imagereproduced at the image plane position DF2 is relatively farther awayfrom the user's eyes, and assuming that, in this condition, a distancebetween the image plane position DF2 and the user's eyes is 280 cm to320 cm, such that it is ensured that the user's eyes can clearly see theimage which is relatively farther away from the user's eyes.

In the embodiment shown in FIG. 2, each display group 01 is consisted oftwo display units 10, an image plane position of one display unit 10 ofthe two display units is DF1, an image plane position of the otherdisplay unit 10′ of the two display units is DF2; further, each displayunit 10 includes two adjacent pixels 101. An Example will be describedin detail in conjunction with the embodiment shown in FIG. 2.

When the image reproduced by the holographic display panel needs to havethe image plane position DF1, both of the two pixels 101 of the displayunit 10 having the image plane position DF1 are turned on, and both ofthe two pixels 101 of the display unit 10′ having the image planeposition DF2 are turned off, such that, in the holographic displaypanel, only the display unit 10 having the image plane position DF1 canemit light, and therefore the image reproduced by the holographicdisplay panel has the image plane position DF1.

When the image reproduced by the holographic display panel needs to havethe image plane position DF2, both of the two pixels 101 of the displayunit 10′ having the image plane position DF2 are turned on, and both ofthe two pixels 101 of the display unit 10 having the image planeposition DF1 are turned off, such that, in the holographic displaypanel, only the display unit 10′ having the image plane position DF2 canemit light, and therefore the image reproduced by the holographicdisplay panel has the image plane position DF2.

When the image reproduced by the holographic display panel needs to havethe image plane position DF1 and the image plane position DF2, the twopixels 101 of the display unit 10 having the image plane position DF1and the two pixels 101 of the display unit 10′ having the image planeposition DF2 are turned on, such that, in the holographic display panel,both of the display unit 10 having the image plane position DF1 and thedisplay unit 10′ having the image plane position DF2 can emit light, andtherefore the image reproduced by the holographic display panel has theimage plane position DF1 and the image plane position DF2.

When the image reproduced by the holographic display panel needs to havean image plane position DF3 located between the image plane position DF1and the image plane position DF2 (as shown in FIG. 2), it can beachieved by the following manner.

FIG. 7 shows an arrangement of display units (see the left drawing ofFIG. 7), and each display unit includes two pixels 101 (see the rightdrawing of FIG. 7). FIG. 7 shows two different display units 10, 10′,which have the first image plane position DF1 and the second image planeposition DF2 respectively. As shown in the right drawing of FIG. 7, onepixel 101 of the display unit 10 having the image plane position DF1 isturned on (the pixel 101 which is turned on has no color), the otherpixel 101 is turned off, and one pixel 101 of the display unit 10′having the image plane position DF2 is turned on and the other pixel 101is turned off. Further referring to FIG. 2, the upper pixel of thedisplay unit 10 having the image plane position DF1 is turned on and thelower pixel of the display unit 10 having the image plane position DF1is turned off, and the lower pixel of the display unit 10′ having theimage plane position DF2 is turned on and the upper pixel of the displayunit 10′ having the image plane position DF2 is turned off. A reverseextension line of light emitted from the upper pixel 101 of the displayunit 10 that is turned on and a reverse extension line of light emittedfrom the lower pixel 101 of the display unit 10′ that is turned onintersect at the image plane position DF3 between the image planeposition DF1 and the image plane position DF2, after passing throughrespective phase plates 102, such that the image reproduced by theholographic display panel has the image plane position DF3. Adjustmentof other image plane positions between the image plane position DF1 andthe image plane position DF2 is similar to the above-described mannerand will not be repeated herein. Obviously, the image plane position DF3can be obtained by combining two pixels located in different displayunits 10.

In the case that each display unit 10 includes three pixels 101 and thephase plate 102 is arranged at the side of the color filter layer 103facing away from the color filter layer 103, as shown in FIG. 8, lightemitted from the backlight source 13 first passes through the colorfilter layer 103 and then arrives at the phase plate 102 (for example,the phase plate 102 is a transmission grating). With the light filteringfunction of the color filter layer 103, light of different colorsirradiates to different phase plates 102. For example, in the case thatthe pixel 101 includes a red sub-pixel, a green sub-pixel and a bluesub-pixel, the pixel 101 can emit red light, green light and blue light.Since red light, green light and blue light have different wavelengthsλ, light arrives at the phase plate 102 has different wavelengths λ. Inorder to make light emitted by three sub-pixels 1011 of the same onepixel 101 (for example, the left pixel 101) to have the same diffractiveangle β after passing through respective phase plates 102, periods P ofthree phase plates 102 corresponding to the three sub-pixels 1011 needto be changed, such that periods P of the three phase plate 102 aredifferent from each other. For example, since the wavelength λ of thered light is larger than those of the green light and the blue light,the period P of the phase plate 102 corresponding to the red sub-pixelneeds to be enlarged while periods of the phase plates 102 correspondingto the blue sub-pixel needs to be reduced, when a diffractive angle β ofthe green light after passing through the phase plate 102 is used as areference. Therefore, periods P of phase plates 102 in the same displayunit 10 shown in FIG. 8 are different from each other.

In another embodiment shown in FIG. 9, the display group 01 may includethree different display units 10, each of which has three differentimage plane positions, i.e., an image plane position DF1, an image planeposition DF2 and an image plane position DF3. In this case, as shown inFIG. 9, one pixel 101 of each of the three display units 10 are turnedon (the pixel 101 that is turned on is not applied with any color), suchthat diffractive angles β of outcoming light emitted by pixels 101,which are turned on, are different from each other after passing throughrespective phase plates 102, and thereby, reverse extension lines of theoutcoming light having the above three different diffractive angles βintersect at an image plane position DF4. As a conclusion, the imageplane position DF4 can be obtained through a combined use of the pixels101 located in the three different display units 10. Further, the aboveembodiment is described as an example, in which the image plane positionDF4 is determined by the intersection point of the reverse extensionlines of the pixels 101 in three different display units 10, and ofcourse, light emitted from every two of the three pixels 101 in thethree display units 10 may also intersect at different points, such thatimage plane positions other than the image plane position DF1, the imageplane position DF2 and the image plane position DF3 can be determined,which is in favor of diversity of adjustment of the image planepositions.

To be noted, when a display group 01 is consisted of more than threedifferent display units 10 having different image plane positions,adjustment of image plane positions is similar to that described aboveand will not be repeated herein.

In order to combine a pixel 101 of one display unit 10 with a pixel 101of any display unit 10 adjacent to the one display unit 10, preferably,as shown in FIG. 7 or 9, one display unit 10 has an image plane positiondifferent from that of any display unit 10 adjacent to the one displayunit 10.

As a conclusion, since image plane positions of display units 10 in thesame display group 01 are different from each other, when ON or OFFstates of the display units 10 of the display units 10 in the samedisplay group 01 are controlled, a plurality of image plane positionsfor holographic display can be defined by the same one display group 01,such that the stereoscopic effect of a dynamic holographic display canbe improved.

The following is an example used to describe an arrangement ofsub-pixels 1011 forming the above described pixel 101.

In one embodiment, in the case that a plurality of sub-pixels 1011forming the pixel 101 includes first sub-pixels (for example, redsub-pixels R), second sub-pixels (for example, green sub-pixels G) andthird sub-pixels (for example, blue sub-pixels B), as shown in FIG. 10,in one row of two adjacent sub-pixel rows, the first sub-pixels R andthe second sub-pixels G are arranged alternately, while in the other rowof the two adjacent sub-pixel rows, there are only the third sub-pixelsB. additionally, three sub-pixels of each pixel 101 is arranged in atriangle arrangement, as shown in FIG. 10.

In this case, when each display unit 10 includes two adjacent pixels, asshown in FIG. 10, the two adjacent pixels may be a pixel 101 and a pixel101′ adjacent to one another in a same horizontal direction, or they maybe the pixel 101 and a pixel 101″ adjacent to one another in differenthorizontal directions. Further, when each display unit 10 includes threeadjacent pixels, as shown in FIG. 10, the three adjacent pixels mayinclude the pixel 101 and the pixel 101′ that are adjacent to oneanother in a same horizontal direction, and the pixel 101″ adjacent tothe pixel 101 and the pixel 101′ in a different horizontal direction. Ofcourse, the above embodiment is just an illustration taking each displayunit 10 including two or three adjacent pixels 101 as an example, and inthe case that one display unit 10 includes a different number of pixels101, the display unit 10 may be divided similarly as above, which willnot be repeatedly described herein.

In another embodiment, a plurality of sub-pixels 1011 forming the pixel101 may be arranged in order. Specifically, in a case where thesub-pixels 1011 include first sub-pixels (for example, red sub-pixelsR), second sub-pixels (for example, green sub-pixels G) and thirdsub-pixels (for example, blue sub-pixels B), as shown in FIG. 11, thefirst sub-pixels R, the second sub-pixels G and the third sub-pixels Bare arranged in order.

In this case, when each display unit 10 includes two adjacent pixels, asshown in FIG. 11, the two adjacent pixels may be a pixel 101 and a pixel101 adjacent to one another in a same horizontal direction, or they maybe the pixel 101 and a pixel 101′ adjacent to one another in differenthorizontal directions. Further, when each display unit 10 includes threeadjacent pixels, as shown in FIG. 10, the three adjacent pixels mayinclude three pixels 101 arranged in order in a same horizontaldirection, or it may include two pixels 101 adjacent to one another in asame horizontal direction and the pixel 101′ adjacent to the pixels 101in a different horizontal direction. Of course, the above embodiment isjust an illustration taking each display unit 10 including two or threeadjacent pixels 101 as an example, in the case that one display unit 10includes a different number of pixels 101, the display unit 10 may bedivided similarly as above, which will not be repeatedly describedherein.

An embodiment of the present disclosure provides a holographic displaydevice, which includes the holographic display panel according to anyone of the above described embodiment, such that the display device hasa similar structure and the same beneficial effect as the holographicdisplay panel provided in previous embodiment. Since the structure andbeneficial effect of the holographic display panel have been describedin detail in the above embodiments, they will not be repeated herein.

On this basis, the holographic display panel may include an organiclight emitting diode display panel or a liquid crystal display panel. Inthe case that the holographic display panel includes a liquid crystaldisplay panel, the holographic display device further include abacklight source 13, as shown in FIG. 12, which is configured to providebacklight to the liquid crystal display panel and to provide thereference light when the holographic display panel is reproducing aholographic image. The present disclosure is not limited by the type ofthe backlight source 13, which may be of a direct type or an edge typein structure, and may be a surface light source or a light source array.Additionally, when performing a hologram calculation, characteristics ofthe reference light provided by the backlight source 13 need to beconsidered. Since characteristics of a collimated light are relativelysimple, when the backlight source 13 is a direct backlight source,preferably, the backlight source 13 is a collimated light source, so asto reduce difficulty in the hologram calculation.

In such a manner, before display, coded information of a holographicimage obtained through hologram calculation may be converted intovoltage data applied to respective sub-pixels of the pixel. When theholographic image changes, the coded information changes accordingly,such that voltage data applied to respective sub-pixels in the liquidcrystal display panel 20 shown in FIG. 12 also varies, and thereby adynamic holographic display can be achieved. Moreover, when theholographic display panel is used to perform a holographic display, thebacklight source 13 can provided the reference light for thereproduction of the holographic image, and the reference light can beirradiated to the phase plate 102 through the liquid crystal displaypanel 20. By adjusting the phase plate 102, diffractive angle β ofoutcoming light from the phase plate can be controlled, such thatreverse extension lines of light emitted from the same display group 10intersect at a same image plane position. For example, reverse extensionlines of light emitted from the display group 10 having the image planeposition DF1 intersect at the image plane position DF1, and reverseextension lines of light emitted from the display group 10 having theimage plane position DF2 intersect at the image plane position DF2.Therefore, a spatial location of a holographically displayed image maybe defined by the image plane positions. On this basis, since imageplane positions of respective display units in the same display groupare different from each other, a plurality of spatial locations of aholographically displayed image can be defined by the same display groupthrough controlling the ON and OFF states of pixels in respectivedisplay units of the same display group, such that the stereoscopiceffect of the dynamic holographic display can be improved.

In another aspect, the present disclosure also provides a display methodthat can be applied to the holographic display device according to anyone of the above described embodiments. As shown in FIG. 13, the methodincludes:

S101: obtaining coded information of a holographic image, the codedinformation including: gray scale value of each pixel 101 in eachfeature area of the image, wherein the gray scale value is superimposedwith image plane position data of the feature area, and additionally,the image plane position data of one feature area indicates only oneimage plane position.

To be noted, the coded information of the holographic image is obtainedthrough a hologram calculation. Hologram calculation means calculating aholographic image by using a computer. The hologram calculation does notneed substantial existence of an object, the holographic image can bedrawn after inputting a mathematical description of an object wave intothe computer, and then the holographic image can be reproduced by anoptical means.

Specifically, drawing a holographic image by hologram calculationincludes the following steps:

first, obtaining values of an object or a wave surface at discretesampling points by sampling;

then, calculating light distribution of the object light wave in aholographic plane;

then, encoding, i.e., encoding complex amplitude distribution of thelight wave in the holographic plane into transmissivity variations ofthe holographic image;

finally, forming an image, specifically, drawing an image with thetransmissivity variations of the holographic image under control of acomputer. While drawing the image with the transmissivity variations ofthe holographic image, gray scale values of respective sub-pixels of theimage that is drawn are determined.

Moreover, the above mentioned feature area means that an effectivedisplay region of the display panel for displaying the whole image isdivided according to features of the image to be displayed, and thefeature area is an area having a closed boundary, and one feature areahas only one image plane position.

For example, a holographic image to be reproduced includes the followingfeatures: a person located nearby, a mountain far away, and waterbetween the person and the mountain. In this case, the effective displayregion may be divided into a first feature area where the person islocated, a second feature area where the mountain is located, and athird feature area where the water is located. Image plane positionsindicated by image plane position data of the first feature area, secondfeature area and third feature area are different from each other. Forexample, the image plane positions indicated by image plane positiondata of the first feature area is the image plane position DF1 shown inFIG. 2, the image plane positions indicated by image plane position dataof the second feature area is the image plane position DF2, the imageplane positions indicated by image plane position data of the thirdfeature area is the image plane position DF3. A distance between theimage plane position DF1 and the user's eyes is the shortest, a distancebetween the image plane position DF2 and the user's eyes is the longest,and a distance between the image plane position DF3 and the user's eyesis intermediate.

Assuming that the display group 01 consists of two display units 10, animage plane position of one display units 10 is DF1, an image planeposition of the other display unit 10′ is DF2, and each display unit 10includes two adjacent pixels 101. A method of superimposing an imageplane position of a feature area to obtain the gray scale value of eachpixel 101 in the feature area will be described hereinafter.

For example, for the first feature area where the feature person islocated, the image plane positions indicated by the image plane positiondata of the first feature area is the image plane position DF1,therefore, in the first feature area, both pixels 101 in the displayunit 10 shown in FIG. 2, which has the image plane position DF1, areturned on, and both pixels 101 in the display unit 10′, which has theimage plane position DF2, are turned off, such that at a position in theholographic display panel corresponding to the first feature area, onlythe display unit 10 having the image plane position DF1 can emit light,thus, gray scale values of the pixels 101 of the display unit 10, whichhas the image plane position DF1, are superimposed with the image planeposition data, such that an image reproduced at the position of theholographic display panel corresponding to the first feature area hasthe image plane position DF1 indicated by the image plane position data.

Further, for the second feature area where the feature mountain islocated, the image plane positions indicated by the image plane positiondata of the second feature area is the image plane position DF2,therefore, in the second feature area, both pixels 101 in the displayunit 10′ shown in FIG. 2, which has the image plane position DF2, areturned on, and both pixels 101 in the display unit 10, which has theimage plane position DF1, are turned off, such that at a position in theholographic display panel corresponding to the second feature area, onlythe display unit 10′ having the image plane position DF2 can emit light,thus, gray scale values of the pixels 101 of the display unit 10′, whichhas the image plane position DF2, are superimposed with the image planeposition data, such that an image reproduced at the position of theholographic display panel corresponding to the second feature area hasthe image plane position DF2 indicated by the image plane position data.

Additionally, when the image plane position indicated by the image planeposition data of the feature area is different from the image planeposition of any display unit 10, the method of superimposing an imageplane position of a feature area to obtain the gray scale value of eachpixel 101 in the feature area includes selecting and turning on onepixel 101 of each display unit of at least two display units 10, suchthat reverse extension lines of the light outcoming from the phaseplates 102 corresponding to the pixels 101 that are turned on intersectat an image plane position indicated by the image plane position data ofthe feature area.

Specifically, for the third feature area where the feature water islocated, the image plane positions indicated by the image plane positiondata of the third feature area is the image plane position DF3, but thedisplay group 01 only include the display unit 10 having the image planeposition DF1 and the display unit 10′ having the image plane positionDF2. Therefore, the image plane position indicated by the image planeposition data of the third feature area is different from the imageplane position of any one of the display units 10. In this case, sincethe image plane position DF3 is located between the image plane positionDF1 and the image plane position DF2, as shown in FIG. 7, one of thepixels 101 of the display unit 10 having the image plane position DF1 isturned on and the other one of the pixels 101 is turned off, and one ofthe pixels 101 of the display unit 10′ having the image plane positionDF2 is turned on and the other one of the pixels 101 is turned off, suchthat gray scale values of the pixels 101 of the display unit 10 havingthe image plane position DF1 and the pixels 101 of the display unit 10′having the image plane position DF2 are superimposed with the imageplane position data.

In this circumstance, as shown in FIG. 2, a reverse extension line ofthe light emitted by the pixel 101, which is turned on, of the displayunit 10 having the image plane position DF1 and a reverse extension lineof the light emitted by the pixel 101, which is turned on, of thedisplay unit 10′ having the image plane position DF2 intersect at theimage plane position DF3 after passing through respective phase plates102 corresponding to the pixels that are turned on, such that an imagereproduced at the position of the holographic display panelcorresponding to the third feature area has the image plane position DF3indicated by the image plane position data.

Adjustment of other image plane positions located between the imageplane position DF1 and the image plane position DF2 are similar to themanner described above, and will not be repeated herein.

The method further comprises:

S102: converting the gray scale value of each pixel 101 into voltagedata Vdata of each sub-pixel 1011 in the pixel 101; and

S103: charging each sub-pixel 1011 in the pixel 101 in accordance withthe voltage data Vdata during progressively scanning rows of sub-pixels1011.

During performing the step 103, as shown in FIG. 12, the backlightsource 13 may provide reference light, and the liquid crystal displaypanel 20 can control color and gray scale of each sub-pixel 1011, suchthat the image reproduced by the liquid crystal display panel 20 matchesthe holographic image drawn in the step S101, and thereby a reproductionprocess of the holographic display is achieved.

In such a manner, the coded information of the holographic imageobtained through a hologram calculation can be converted into voltagedata of each sub-pixel in the pixel. In this case, when the holographicimage changes, the coded information changes accordingly, such that thevoltage data of each sub-pixel also changes, and thereby a dynamicholographic display can be achieved.

As shown in FIG. 3, each display unit 10 of the holographic displaypanel further comprises a plurality of phase plates 102, and these phaseplates 102 may be used to adjust diffractive angles β of light comingout of the phase plates 102, so as to adjust a distance between an imageplane position (image plane position DF1), which is an intersectionpoint of reverse extension lines of light emitted from the same onedisplay unit 10, and human's eyes, such that the image reproduced by theholographic display panel has a certain stereoscopic effect. When theholographic display panel has a display unit 10 having a plurality ofdifferent image plane positions, an even better stereoscopic effect canbe achieved.

Although several exemplary embodiments have been shown and described incombination with the drawings, it would be appreciated by those skilledin the art that various changes or modifications may be made in theseembodiments without departing from the principles and spirit of thedisclosure, the scope of which is defined in the claims and theirequivalents.

1. A holographic display panel, comprising a plurality of display units,each of the plurality of display units comprising: at least two adjacentpixels each comprising a plurality of sub-pixels; and a plurality ofphase plates, each sub-pixel of the plurality of sub-pixelscorresponding to one of the plurality of phase plates in a light exitdirection of the sub-pixel, the plurality of phase plates beingconfigured to control diffractive angles of light coming out of theplurality of phase plates, wherein diffractive angles of light comingout of the phase plates corresponding to the sub-pixels in one samepixel are the same, and a diffractive angle of first light coming out ofthe phase plates corresponding to a first pixel in one of the pluralityof display units is different from a diffractive angle of second lightcoming out of the phase plates corresponding to a second pixel that isdifferent from the first pixel and is in the same display unit as thefirst pixel, and a reverse extension line of the first light and areverse extension line of the second light intersect at an image planeposition.
 2. The holographic display panel according to claim 1, whereinthe plurality of display units are divided into a plurality of displaygroups arranged into an array, each of the plurality of display groupsincludes at least two display units, and the at least two display unitsare located adjacent to each other; and wherein image plane positions ofthe display units in a same one of the plurality of display groups aredifferent from each other.
 3. The holographic display panel according toclaim 2, wherein a first display unit of the plurality of display unitshas an image plane position different from an image plane position ofany one of the display units adjacent to the first display unit.
 4. Theholographic display panel according to claim 1, wherein each pixelcomprises a first sub-pixel, a second sub-pixel and a third sub-pixel;the first sub-pixels, the second sub-pixels and the third sub-pixels inthe holographic display panel are arranged in two adjacent rows, andwherein the first sub-pixels and the second sub-pixels are arrangedalternately in a first row of the two adjacent rows, and a second row ofthe two adjacent rows is constituted only by the third sub-pixels; andthe third sub-pixel of each pixel is located between the first sub-pixeland the second sub-pixel of the same pixel in a direction of the rows.5. The holographic display panel according to claim 1, wherein theplurality of sub-pixels of each pixel are arranged in a same row.
 6. Theholographic display panel according to claim 1, wherein the plurality ofphase plates are transmission gratings.
 7. The holographic display panelaccording to claim 1, further comprising an array substrate and a colorfilter substrate disposed opposite to the array substrate; wherein thecolor filter substrate comprises a color filter layer and the pluralityof phase plates, and the plurality of phase plates are disposed at aside of the color filter layer close to or facing away from the arraysubstrate.
 8. A holographic display device, comprising the holographicdisplay panel according to claim
 1. 9. The holographic display deviceaccording to claim 8, wherein the holographic display panel comprises aliquid crystal display panel and a collimated backlight sourceconfigured to provide backlight to the liquid crystal display panel. 10.A holographic display method for the holographic display deviceaccording to claim 8, wherein the method comprises: obtaining codedinformation of a holographic image, the coded information comprising agray scale value of each pixel in each feature area of the image,wherein the gray scale value is superimposed with image plane positiondata of the feature area, and the image plane position data of onefeature area indicates only one image plane position; converting thegray scale value of each pixel into voltage data of each sub-pixel inthe pixel; and charging each sub-pixel in the pixel in accordance withthe voltage data during progressively scanning rows of sub-pixels. 11.The method according to claim 10, wherein the plurality of display unitsare divided into a plurality of display groups arranged into an array,each of the plurality of display groups includes at least two displayunits having different image plane positions, each of the plurality ofdisplay units comprising at least two adjacent pixels, an image planeposition indicated by image plane position data of the feature area isdifferent from an image plane position of any of the plurality ofdisplay units, and the method of superimposing an image plane positionof the feature area to obtain the gray scale value of each pixel in thefeature area comprises: selecting and turning on one pixel of eachdisplay unit of the at least two different display units, whereinreverse extension lines of light coming out of the phase platescorresponding to the pixels that are turned on intersect at an imageplane position indicated by the image plane position data of the featurearea.
 12. The holographic display method for the holographic displaydevice according to claim 9, wherein the method comprises: obtainingcoded information of a holographic image, the coded informationcomprising a gray scale value of each pixel in each feature area of theimage, wherein the gray scale value is superimposed with image planeposition data of the feature area, and the image plane position data ofone feature area indicates only one image plane position; converting thegray scale value of each pixel into voltage data of each sub-pixel inthe pixel; and charging each sub-pixel in the pixel in accordance withthe voltage data during progressively scanning rows of sub-pixels. 13.The method according to claim 12, wherein the plurality of display unitsare divided into a plurality of display groups arranged into an array,each of the plurality of display groups includes at least two displayunits having different image plane positions, each of the plurality ofdisplay units comprising at least two adjacent pixels, an image planeposition indicated by image plane position data of the feature area isdifferent from an image plane position of any of the plurality ofdisplay units, and the method of superimposing an image plane positionof the feature area to obtain the gray scale value of each pixel in thefeature area comprises: selecting and turning on one pixel of eachdisplay unit of the at least two different display units, whereinreverse extension lines of light coming out of the phase platescorresponding to the pixels that are turned on intersect at an imageplane position indicated by the image plane position data of the featurearea.
 14. The holographic display device according to claim 8, whereinthe plurality of display units are divided into a plurality of displaygroups arranged into an array, each of the plurality of display groupsincludes at least two display units, and the at least two display unitsare located adjacent to each other; and wherein image plane positions ofthe display units in a same one of the plurality of display groups aredifferent from each other.
 15. The holographic display device accordingto claim 14, wherein a first display unit of the plurality of displayunits has an image plane position different from an image plane positionof any one of the display units adjacent to the first display unit. 16.The holographic display device according to claim 8, wherein each pixelcomprises a first sub-pixel, a second sub-pixel and a third sub-pixel;the first sub-pixels, the second sub-pixels and the third sub-pixels inthe holographic display panel are arranged in two adjacent rows, andwherein the first sub-pixels and the second sub-pixels are arrangedalternately in a first row of the two adjacent rows, and a second row ofthe two adjacent rows is constituted only by the third sub-pixels; andthe third sub-pixel of each pixel is located between the first sub-pixeland the second sub-pixel of the same pixel in a direction of the row.17. The holographic display device according to claim 8, wherein theplurality of sub-pixels of each pixel are arranged in a same row. 18.The holographic display device according to claim 8, wherein theplurality of phase plates are transmission gratings.
 19. The holographicdisplay device according to claim 8, further comprising an arraysubstrate and a color filter substrate disposed opposite to the arraysubstrate; wherein the color filter substrate comprises a color filterlayer and the plurality of phase plates, and the plurality of phaseplates are disposed at a side of the color filter layer close to orfacing away from the array substrate.